Address for correspondence: Rafał Januszek, MD, PhD, 2nd Department of Cardiology and Cardiovascular Interventions, University Hospital, ul. Kopernika 17, 31–501 Kraków, Poland, tel: +48 12 424 71 70, fax:+48 12 424 71 80, e-mail: jaanraf@interia.pl Received: 21.08.2016 Accepted: 13.09.2016
Fractional flow reserve measurement modification with monorail pressure catheter
Magdalena Jędrychowska1, Rafał Januszek1, Łukasz Rzeszutko1, Dariusz Dudek1, 2
12nd Department of Cardiology and Cardiovascular Interventions, University Hospital, Krakow, Poland
2Department of Interventional Cardiology, Jagiellonian University Medical College, Krakow, Poland
A number of symptomatic patients with coro- nary artery disease undergo revascularization without definite evidence that particular coronary stenosis is responsible for their symptoms [1].
Currently, the borderline coronary artery stenoses are most commonly assessed by intravascular ultrasound and fractional flow reserve (FFR) along- side with quantitative coronary angiography [2].
FFR measurement, as performed by pressure wire (PW), requires its multiple removals during FFR and percutaneous coronary intervention (PCI), and results in a relatively high signal drift with loss of
accuracy. The novel exchange microcatheter (RXi) was invented to assess FFR in a safer mode [3, 4].
A 61-year-old man was admitted to hospital with exertional stenocardia. The patient under- went myocardial infarction in 1988 and coronary artery bypass grafting operation in 1999. Angiog- raphy revealed total occlusion of the left anterior descending artery (LAD), as previously. In the right coronary artery (RCA) occurred dissemi- nated, multi-segmental stenoses up to 40% with borderline stenosis of 60% in the distal portion (Fig. 1A). The aorto-marginal saphenous vein
Figure 1. Fluoroscopic images of the right coronary artery (RCA); A. Cine image of stenosed RCA; B. Cine image of RCA and the Acist Navvus microcatheter during the measurement, and its distal part with the radiopaque marker (labe- led with white arrow); C. Cine image of RCA after angioplasty with stent deployment (marked with white arrow); D. Frac- tional flow reserve (FFR) of distal part of RCA before stent implantation. E: FFR of distal part of RCA after stent implantation;
Pa — pressure proximal to the lesion; Pd — pressure distal to the lesion; Pv — coronary venous pressure.
CLINICAL CARDIOLOGY
Cardiology Journal 2016, Vol. 23, No. 6, 618–619
DOI: 10.5603/CJ.2016.0102 Copyright © 2016 Via Medica ISSN 1897–5593
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LETTER TO THE EDITOR
graft (SVG Ao-Mg) graft was occluded. The Acist Navvus microcatheter (ACIST Medical Systems, Eden Prairie, MN, USA) was used to perform FFR measurements in RCA. Two intracoronary boluses of adenosine were administered dur- ing the procedure: 200 µg and 400 µg. The final result was as follows: 0.74 confirmed the signifi- cance of RCA stenosis (Fig. 1D). Simultaneously, PCI of the distal RCA segment was performed.
After predilatation with non-compliant balloon catheter 2.5 × 15 mm 16 atm, DES CID Cre8 (Carbostent&Implantable Devices, Saluggia, Italy) 3.0 × 20 mm 16 atm was deployed (Fig. 1B, C).
Control FFR after intracoronary administration of 400 µg of adenosine was 0.85, which confirmed that culprit lesion was treated (Fig. 1E).
The FFR is recommended for the assessment of borderline coronary lesions (stenoses between 40% and 70%) by international European cardiol- ogy societies [5]. It has been shown that FFR- -guided PCI results in significantly lower rates of death and myocardial infarctions than PCI, based on angiographic assessment alone in 4-year follow- up [6]. The FFR-guided PCI coexisting with the optimal medical therapy is the most favorable ap- proach in patients with stable angina, remarkably reducing the need of urgent revascularizations [7].
In individuals with disseminated, multi-segmental and borderline stenoses, the pull-back method with continuous recording of coronary artery pressure is used for FFR measurement. The gold standard is continuous intravenous adenosine infusion, where- as intracoronary infusion of adenosine bolus is a shorter modification that brings the similar propor- tion of stenosis when high doses of adenosine bo- luses are administered [8]. It was revealed that high boluses of intracoronary adenosine up to 600 µg are safe for the patient [8]. Devices intended to be applied for FFR measurement are underutilized due to inconvenient usage. It could be caused by difficulties in PW delivery in tortuous and narrowed arteries and susceptibility to kinking [3]. Further- more, PCI requires withdrawal of the PW and may cause complications due to this maneuver. The RXi™
system is a new FFR technology, where ultrathin monorail microcatheter is a key part of the device.
The RXi microcatheter could be used with differ- ent guide-wires (GWs), which are appropriate for the particular artery anatomy and morphology [3].
It is noteworthy, that the RXi microcatheter is compatible with standard 0.014” GWs. The Mi- crocatheter Navvus is elliptically-shaped. The 0.020” × 0.025” dimensions are comparable to the diameter of 0.022” circular-shaped wire. The fiber optic sensor is attached 5 mm from the
distal tip and the radiopaque marker 2.5 mm from the distal tip [4]. The RXi microcatheter has a significant advantage in creating the possibility to obtain measurements without loss of wire access to the artery [4]. The FFR measured after coronary stenting is a clinically important tool to evaluate the results of the coronary intervention. However, the measurement of FFR after stent implantation requires re-crossing the stent with PW which entails a significant risk of its incorrect position or, in the case of stenting by PW itself re-connecting the FFR system, increases the likelihood of signal drift. RXi microcatheters allow the FFR measurement after revascularization using the same wire which was used during stent implantation, eliminating the need to re- cross the coronary artery or to disconnect the FFR system. Moreover, if it is necessary to re-place the RXi microcatheter in the vessel, there is no need for re-calibration [4]. Some doubts may arise if the larger diameter affects FFR value. A recently published study from New Zealand showed no influence of the Navvus Microcatheter’s dimensions on the results obtained by FFR. In addition, a good correlation be- tween the results obtained with the new method and a standard PW was noticed [3]. However, the larger diameter of the catheter may cause some difficul- ties with passing to the peripheral part of narrowed, calcified and tortuous arteries as compared to PWs alone, which may in some cases limit the use of RXi microcatheter.
Conflict of interest: None declared
References
1. Pijls NH, De Bruyne B, Peels K et al. Measurement of fractional flow reserve to assess the functional severity of coronary-artery stenoses.
N Engl J Med, 1996; 334: 1703–1708.
2. Legutko J, Jąkała J, Mrevlje B et al. Fractional flow reserve-guided myocardial revascularization. Post Kardiol Interw, 2011; 7: 228–241.
3. Menon M, Jaffe W, Watson T, Webster M. Assessment of coronary fractional flow reserve using a monorail pressure catheter: The first- in-human ACCESS-NZ trial. EuroIntervention, 2015; 11: 257–263.
4. Diletti R, Van Mieghem NM, Valgimigli M et al. Rapid exchange ultra-thin microcatheter using fibre-optic sensing technology for measurement of intracoronary fractional flow reserve. EuroIntervention, 2015; 11: 428–432.
5. Wijns W, Kolh P, Danchin N et al. Task Force on Myocardial Revasculari- zation of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS); European Asso- ciation for Percutaneous Cardiovascular Interventions (EAPCI), Guide- lines on myocardial revascularization. Eur Heart J, 2010; 31: 2501–2555.
6. De Backer O, Biasco L, Lønborg J et al. Long-term outcome of FFR- -guided PCI for stable coronary artery disease in daily clinical practice:
A propensity score-matched landmark analysis. EuroIntervention, 2016; 11: 1257–1266.
7. De Bruyne B, Pijls NH, Kalesan B at al.; FAME 2 Trial Investi- gators. Fractional flow reserve-guided PCI versus medical therapy in stable coronary disease. N Engl J Med, 2012; 367: 991–1001.
8. Leone AM, Porto I, De Caterina AR et al. Maximal hyperemia in the assessment of fractional flow reserve: Intracoronary adenosine versus intracoronary sodium nitroprusside versus intravenous adenosine:
The NASCI (Nitroprussiato versus Adenosina nelle Stenosi Coronar- iche Intermedie) study. JACC Cardiovasc Interv, 2012; 5: 402–408.
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Magdalena Jędrychowska et al., Fractional flow reserve measurement modification with monorail pressure catheter
